Sarthaks Test
0 votes
in Arithmetic Progression by (7.9k points)
closed by

The 24th term of an A.P. is twice its 10th term. Show that its 72nd term is 4 times its 15th term.

1 Answer

+1 vote
by (8.1k points)
selected by
Best answer


a24 = 2a10

a +23d = 2(a +9d)

5d = a (i)

To Prove:

a72 = 4a15


L.H.S. = a72

= a +71d

= 5d +71d [from (i)]

= 76d

R.H.S = 4a15

= 4(a +14d)

= 4a +56d

= 4(5d) +56d [from (i)]

= 20d +56d

= 76d

Since, L.H.S = R.H.S.

Hence proved

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.